In industry, many and varied types of connections provide mechanical attachment as well as thermal and/or electrical conduction. Such connections are especially evident in the electronics industry where tiny packages often include a plurality of external contacts for connection to a circuit assembly. Such external contacts are becoming more densely arranged on a package and adapting them for connection has become a significant problem.
On a typical electronic package (referred to herein as a device), the contacts are disposed in rows extending along the edges of a rectangular surface. Such contacts are typically flat metal pads which are later bonded to similar contacts in a circuit assembly, e.g., a substrate such as a ceramic slab or a printed circuit (P-C) board. To prepare for such bonding, it is conventional to fuse a preformed body of bonding material to each contact on either the device or a P-C board, though more often on the device itself. Later, when the device is mounted, the array of such bodies are simultaneously heated and the material is reflowed to form mechanically sound and conductive connections between the contacts of the device and those of the P-C board.
A problem with electronic devices is that the preformed bodies are typically 10-40 mils in diameter which makes them very difficult to handle efficiently. Another problem is that the bodies are sometimes irregular in shape or out of alignment with a contact. Consequently, unwanted cross connections occur between adjacent bodies either initially or later during reflow bonding of the device to a circuit assembly. It will be appreciated that keeping connections isolated from one another is an important consideration in electronics work.
A further consideration for many such connections is that there be a defined distance between respective contacts of a device and those of a circuit assembly. For example, when a device is mounted to a P-C board, a clearance space is often required between the board and the body of the device for cleaning purposes. Conditions of heat and pressure in reflow bonding are difficult to control well enough to always achieve a well-defined distance between such contacts. To solve this problem, bodies of bonding material having a hard core are sometimes utilized. The dimensions of the core remain substantially unchanged to define a desired minimum distance between respective contacts when connection is made therebetween. However, such hard core bodies cause similar problems to those encountered with the conventional bodies. They are so small that they are difficult to handle efficiently while achieving a required isolation between bodies.
Consequently, it is desirable to provide new and improved expedients for adapting contacts for bonding other contacts thereto. It is also desirable to adapt contacts for connection to other contacts while maintaining isolation between adjacent connections. It is further desirable to adapt first contacts for connection to second contacts wherein a defined distance is maintained between respective first and second contacts.